Yes that is a 1989 Giro with Athena groupset. The post is Athena as well. I bought one from the original owner about 9-10 years ago kind of the same way. He gave me the original pedals, catalog, original freewheel in the box too! If you look at that catalog closely, you’ll notice that the SLX frameset is the same as the two models above it in the hierarchy, Mondiale and Superleggera. They just differed in a little higher end components. I got mine for $300 and was super excited about that price. On mine, seller had one or two other contacts about it right away but he sold to me as I responded first. I’d think about $600 each would be fair to both parties.
__________________
N = '96 Colnago C40, '04 Wilier Alpe D'Huez, '10 Colnago EPS, '85 Merckx Pro, '89 Merckx Century, '86 Tommasini Professional, '04 Teschner Aero FX Pro, '05 Alan Carbon Cross, '86 De Rosa Professional, '82 Colnago Super, '95 Gios Compact Pro, '95 Carrera Zeus, '84 Basso Gap, ‘89 Cinelli Supercorsa, ‘83 Bianchi Specialissima, ‘VO Randonneur, Ritchey Breakaway Steel, '84 Paletti Super Prestige, Heron Randonneur